The effects of argon pre-annealing on the superconductive properties of plasma-sprayed Y-Ba-Cu-oxide coatings

Plasma spray processing methods and their capacity to produce large quantities of coatings are discussed. It is noted that the thickness of the coating can be varied from tens of microns to millimeters and greater and that complicated geometries can be coated using a computerized robotic system. The as-sprayed Y-Ba-Cu-oxide coatings are mostly in the substitution tetragonal phase, YBa(2-x)Y(x)Cu3O(y). Postspray oxygen-annealing of this phase below 960 C is found to result in a poorly superconducting orthorhombic phase. It is shown, however, that the decomposition of the superconducting phase can be achieved by argon preannealing at 850 C, and subsequent oxygen annealing in the temperature range between 930C and 970C results in orthorhombic superconducting phase with the Tc of about 90K and intragranular J(c) on the order of 1,000,000 A/sq cm.